Voltage regulation circuit



' Jan. 11, 1966 D. D. NYE, JR

VOLTAGE REGULATION CIRCUIT Filed May 11. 1961 FIME/VCY 047EC77/V6 OM17- INVENTOR OUOLEY D. A/YE JA.

BY Siva-M, g

ATTORNEYS United States Patent 3,229,185 VOLTAGE REGULATION CIRCUIT Dudley D. Nye, Jr., Fort Lauderdale, Fla., assiguor to Airpax Electronics Incorporated, Fort Lauderdale, Fla, a corporation of Maryland I Filed May 11, 1961, Ser. No. 109,395 1' Claim. (Cl. 321'-18) This invention relates to voltage regulating circuits, and more particularly to voltage regulating circuits utilizing Zener diodes.

Prior voltageregulating circuits have been used to obmm a regulated power supply which is independent of sec- 0nd order effect of power supply or input line voltage variations. However, these voltage regulating circuits have certain disadvantages and drawbacks. In order to obtain a regulated power supply independent of input line voltage variations, a plurality of Zener diodes and/or feedback techniques have had to be utilized. These techniques have proven to be very complex and expensive.

No less complicated or less expensive alternative way has been suggested that will provide a regulated power supply which is independent of the second order of supply line on input line voltage variations.

The present invention provides a simple and inexpensive way for making the output of a voltage regulating circuit independent of input line voltage variations.

A current-path means which consists of an injection resistor, is connected between a rectified A.C. power source and the output of the voltage regulating circuit. Voltage variations in the A.C. power supply are reflected through the regulating circuit and appear as current changes at the output of the regulating circuit. These voltage variations in the A.C. power supply also cause current changes in the injection resistor, which isconnected to the output of the regulating circuit. The current changes in the injection resistor can be set to compensate for the offset current changes, in the regulating circuit, due to the A.C. power supply variations; With suitable voltage stabilization achieved at the output, the regulating circuit requires only one Zener diode as a shunt regulating element. Accord ingly, this invention provides novel means for making the output of the voltage regulating circuit independent of the A.C. power supply or input line volt-age variations. Furthermore, this invention provides a simple and inex pensive regulating circuit which utilizes only one Zener diode to obtain a regulated power supply independent of the second order effect of input line voltage variations.

It is, therefore, the main object of this invention to provide a simple and easy way of making the output of 21 voltage regulating circuit independent of power supply or input line voltage variations.

Another object of this invention is to provide novel means for making the output of the voltage regulating circuit independent of the A.C. power supply or input line voltage variations.

A further object of this invention is to provide a novel voltage regulating circuit which utilizes only one Zener diode as the regulating element.

A still further object of this invention is to provide a novel voltage regulating circuit which is less complex and less expensive than prior regulating circuits.

Another object of this invention is to provide an improved voltage regulating circuit which features means adapted to supply a compensating current to the output of the regulating circuit so that the output will not change with changes in power supply or input line voltage.

Other objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment of the invention when taken with the drawing which shows in the sole figure a schematic 3,229,185 Patented Jan. 11,- 1966 diagram of a preferred embodiment of a voltage regulating circuit. I I

Referring now to the sole figure, there is shown a Zener diode voltage regulating circuit. The circuit is comprised of a Zener diode 10, a pair of rectifying diodes 6 and 7, and an'input transformer 3. The input transformer 3 consists of primary winding 4 and secondary winding 5. An A.C. power supply or A.C. input supply line voltage is connected to the primary winding 4 of the input transformer 3 through input terminals 1 and 2. The rectifying diode 6 and resistor 8 are connected across the secondary winding 5 0f the input transformer 3. The cathode of rectifying diode 6 is connected to one side of the secondary winding 5, while the anode of the diode 6 is connected to one end of theresistor 8. The other side of the resistor 8 is connected to the other side of secondary winding 5. Smoothing capacitor 18 is connected across resistor 8. Diode 6 rectifies the A.C. voltage appearing across secondary winding 5, which results in a D.C. voltage across resistor 8. The polarity of the DC. voltage across resistor 8 is indicated on the solefigure. The anode of rectifying diode 7 is connected to the common junction of rectifying diode 6 and the secondary winding 5, while the cathode of rectifying diode 7 is connected to the common junction of resistor 9 and smoothing capacitor 1'6. The (function of smoothing capacitor 16 is to filter out or smooththe ripple in the rectified voltage. The regulating circuit requires only one Zener diode 10 as the regulating element. The cathode of Zener diode 10 is connected to the common junction of resistors 9j and 11, while the anode of- Zener diode 10 is connected to capacitor 16. Diode 7 rectifies the A.C. voltage appearing across seconda'ry winding 5, which results in a DC. voltage across Zener diode 10. The polarity of the DC. voltage across Zener diode 10 isindicated in the sole figure. This DC voltage is regulated by the Zener diode 10. The load impedance composed of resistor 13and meter 19 is connected across the Zener diode 10 through resistor 11.- It is appreciated that the load impedance is not restricted to that shown, but may be any other suitable impedance. However, the sole figure demonstrates one ap'plication' of the invention.

A frequency detecting circuit17, providing a DC. current 1 directly proportional to its input frequency, is connected across output terminals 14 and 15, via limiting resistance 20. The voltage regulating circuit supplies a regulated reference current to oppose and bias the output of the frequency detecting circuit 17 such that the total current in meter 19 is zero at a preset frequency. One type of frequency detecting circuit which can be utilized is known as MAGMETER. MAGMETER is a trade name used by Airpax Electronics Incorporated, Fort Lauderdale, Florida, to represent a frequency detecting cir. cuit delivering a DC. output current proportional to the frequency of the input signal. It is appreciated that the circuit 17 is not restricted to a frequency detector, but may be any suitable electrical circuit which requires a voltage regulating circuit whose output is independent of A.C. power supply variations.

To regulate or stabilize the system output current I for changes of reference current 1;, with A.C. input line voltage variations, an injection current-path means is provided and consists of a resistor 12 interconnecting the common junction of the resistor 8 and the diode 6 and the output terminal 14 of the regulating circuit. Resistor 8 is chosen to ensure that the response time of the rectifying circuit utilizing diode 6 is the same as the response time of the rectifying circuit utilizing diode 7 when transient changes of A.C. line voltage occur. With A.C. power supply variations, there will be current changes in resistor 12, which appear at the output terminal 14. The

A.C. power supply variations will also be reflected through the regulating circuit, and appear as small current changes at the output terminal 14. A proper value is chosen for resistor 12 so that its current changes appearing at the output terminal 14 compensate for the oifset current changes appearing at the output terminal 14 due to the [A.C. power supply variations reflected through the voltage regulating circuit. Thus, the invention provides an improved voltage regulating circuit whose output is independent of the A.C. power supply or A.C. input line voltage variations.

The operation of the voltage regulating circuit shown in the sole figure is as follows: An A.C. power supply or A.C. input line voltage is connected across the input terminals 1 and 2. The output of a frequency detecting circuit 17 is connected across the output terminals 14 and 15. The A.C. power supply voltage across input terminals 1 and 2 is fed through input transformer 3. Diode 6 rectified the A.C. voltage so that a DC. voltage appears across resistor 8. The polarity of the DC. voltage across resistor 8 is indicated in the sole figure. Diode 7 rectifies the A.C. voltage so that a DC. voltage appears across Zener diode 10. The polarity of the DC voltage across the regulating Zener diode 10 is indicated in the sole figure as opposite to the polarity of the voltage across resistance 8. Assume there is an increase in the A.C. power supply voltage applied across input terminals 1 and 2. Since a Zener diode departs slightly from its ideal regulating characteristic, the increase in the A.C. power supply voltage is reflected through the regulating circuit and appears as an increase in the regulated voltage across the Zener diode 10. This increase in voltage causes the current 1;; flowing through the resistor 11 to increase. Thus, variaations in the A.C. power supply voltage are reflected through the regulating circuit and also appear as current in the meter 19.

The increase in the A.C. power supply voltage also causes an increase in the DC. voltage across the resistor 8. The common junction of resistor 8 and diode 6 becomes more negative, causing the current I flowing through resistor 12 to increase. This increase in current 1 compensates for the increase in the reference or bias current 1 The increase in injection current 1 permits bias current I to increase without changing current I flowing through the meter load 19. Mathematically, the current entering terminal 14 must be equal to the sum of the currents leaving this terminal. The current I; flowing through meter 19 is now independent of A.C. power supply variations. Thus, this invention provides an improved voltage regulating circuit whose output is independent of A.C. power supply variations. The invention also provides a simple and inexpensive regulating circuit which utilizes only one Zener diode to obtain a regulated power supply independent of the second order eflect of A.C. power supply or input line voltage variations.

The above detailed description of the circuit was for an increase in A.C. power supply voltage. The description is similar for a decrease in A.C. power supply voltage.

Although the present invention has been shown and described in terms of a specific preferred embodiment, changes and modifications which do not depart from the inventive concepts taught herein will suggest themselves to those skilled in the art. Such changes and modifications are deemed to fall within the scope and contemplations of the invention.

What is claimed is:

A voltage regulating circuit comprising an input transformer having a primary circuit for receiving A.C. power and a secondary circuit translating said A.C. power, a shunt rectifying circuit including a diode and a resistor network coupled across said secondary circuit, frequency detecting circuit means, a series rectifying circuit including a diode and a resistor network coupled between said secondary circuit and said frequency detecting circuit means, a Zener diode connected between a point of the 1astmentioned resistor network and a reference point to provide a regulated characteristic to said series rectifying circuit, and resistor coupling means to feed back A.C. power variations reflected in the last-mentioned resistor network to the first-mentioned resistor network to provide further regulation of the regulating circuit.

References Cited by the Examiner UNITED STATES PATENTS 2,945,171 7/1960 Louden 321-19 2,962,649 11/1960 Baum 32l-l6 OTHER REFERENCES 7 Motorola, Silicon Zener Diode and Rectifier Handbook, copyright 1961, 2nd edition, pp. 27--28.

LLOYD MCCOLLUM, Primary Examiner, SAMUEL BERNSTEIN, Examiner, 

